1. Field of the Invention
This invention relates generally to packaging methods and apparatus, and more particularly to wear strips for installation on the fill pipe of form-fill-seal packaging apparatus to extend the life of the transfer belts.
2. Brief Description of the Prior Art
Packing machines of the so-called vertical form-fill-seal class are known in the art. Machines of this type guide a web of flexible packaging material from a supply roll of the material over a forming hood commonly known as a "former", where it is formed into an open ended tubing tubular configuration, intermittently fed downward, sealed to form a longitudinal tube seam, filled with a product, and ultimately sealed at package length intervals and cut into individual packages.
Many machines of the above described type incorporate transfer belts arranged on the sides of the fill tube. These belts are continious belts which are guided over rollers and press the tubular packaging material against the sides of the fill tube. During the movement of the belts, a part of the packaging material is pulled downwardly corresponding to the bag length. The belts must be replaced often due to friction and wear.
There are several patents which disclose packaging machines with formers which are designed to reduce the friction problem in the area of the forming hood.
Tanner, U.S. Pat. No. 3,486,424 discloses a winged former having a tubular removable wear insert within the former positioned to prevent contact and resulting wear by the web of critical guiding areas of the former and preformer portion so as to alleviate the problem of replacement and repair of the former.
Hobart, U.S. Pat. No. 3,962,958 discloses another tube former comprising a body and a detachable wear insert which jointly define a preformer surface over which the web of packaging material is pulled.
Putnam, Jr. et al, U.S. Pat. No. 4,043,098 discloses a packaging machine having vacuum belts. Vacuum belts are perforated and connected to vacuum means for suction gripping of the bag material as it is pulled down over the former. The generally hexagonal fill tube has two elongated narrow side spreaders in the region of the tube engagement with the belts to aid in proper engagement for the suction gripping of the vacuum belts.
Putnam, Jr. et al, U.S. Pat. No. 4,118,913 discloses a packaging machine having vacuum rollers which are perforated and connected to vacuum means for suction gripping of the bag material as it is pulled down over the former. The fill tube has two vertical back-up members in the region of the tube engagement with the rollers for firm engagement over a substantial portion of the roller peripheral surface.
James, U.S. Pat. No. 4,288,965 and British Pat. No. 2,056,940, and Cherney, U.S. Pat. No. 4,546,596, all assigned to Hayssen Manufacturing Co., Sheboygan, Wis., disclose form fill apparatus having vacuum belts arranged on the sides of the fill tube. The belts are guided over rollers and suction grip the bagging material and pull the packaging material downwardly corresponding to the bag length.
East German Pat. No. 156,792 discloses a form fill apparatus having continious belts arranged on the sides of the fill tube, and is directed toward a belt assembly which is easily removable for cleaning. A roller plate is installed between the driving pulley and the idler pulley and cooperates with another roller plate on the fill tube.
Russian Pat. No. 404,711 discloses another fill apparatus having continious belts arranged on the sides of the fill tube, and has a roller plate installed between the driving pulley and the idler pulley which cooperates with a roller plate on the fill tube.
The roller plate devices are undesirable because they are actually disposed on the inside surface of the bagging material as the bag is formed and filled. The rollers accumulate residue which is difficult to remove. Rollers and residue may also become dislodged and accidently packaged in the food product.
The present invention is distinguished over the prior art in general, and these patents in particular by the provision of replaceable wear strips installed on the tube forming apparatus of form, fill and seal packaging machines which have a depending tubular fill pipe through which quantities of product are passed and over which a strip of packaging material is pulled by transfer belts to progressively form the material into a depending and upwardly open tubular configuration and subsequently sealed to form product bearing packages. The wear strips comprise a pair of circumferentially spaced rectangular members removably attached to the fill pipe adjacent the transfer belts to receive substantially the full frictional wearing force caused by the transfer belts pressing and moving the packaging material against the fill pipe. The outer surface of the wear strips are configured to substantially reduce the contact surface area and the resulting wearing of the transfer belt so as to reduce the frequency of replacement and repair of the belts.